1. Field of the Invention
The present invention relates to a thread delivery system or fiber unwinding device, and more specifically to a compact creel system or device for continuous delivery of threads or fibers to a downstream fiber manufacturing process or device.
2. Description of Background Art
Creels are well known in the background art and support packages upon which thread, fiber or yarn is wound for delivery to an associated manufacturing device such as a loom or a diaper machine (note: the terms “thread,” “fiber” and “yarn” are used interchangeably throughout this document). The most common method of unwinding yarn from a cylindrical mandrel (i.e., a “package”) on a creel in manufacturing processes is referred to as “rolling take-off” (RTO) method. In the RTO method, when an active package is exhausted the empty cylindrical mandrel must be removed and a new or standby package is installed. The step of removing the empty mandrel in the RTO method typically requires shutting down the manufacturing process. This shut down of the manufacturing process in the problem of unproductive downtime on a manufacturing line using the RTO method.
In contrast to the RTO method discussed above, an over end take-off (OETO) method allows continuous operation of a manufacturing process. In the OETO method, the terminating end of the fiber wound on the active package is attached to the leading end of the fiber wound on the standby package. Once the active package is completely exhausted, the standby package becomes the new active package without any interruption in the manufacturing process. In this manner, a rather continuous feed of fiber to the manufacturing process is provided.
Background art creels have been provided with various horizontal and vertical arrangements of packages to take advantage of the OETO method. For example, U.S. Pat. Nos. 3,693,904 and 4,450,876 disclose horizontal arrangements of yarn packages configured in pairs for supplying an associated manufacturing process. U.S. Pat. Nos. 3,236,265; 4,358,068; and 4,648,564 disclose vertical arrangements of yarn packages configured in pairs for feeding associated manufacturing process machinery such as looms or diaper machines.
However, with the advent of higher speed manufacturing processes, a configuration of two yarn packages tied together has become increasingly insufficient to supply the associated machinery, and creels with arrangements of four yarn packages tied together have been provided. For example, U.S. Pat. No. 4,545,547 discloses a creel commonly known as a “carousel creel” which includes four yarn packages are configured horizontally and tied together. Moreover, U.S. Pat. Nos. 5,613,643 and 6,634,585 disclose creels using a large number of packages to continuously feed a high speed manufacturing process. However, a problem with carousel and other creels that handle a large number of packages is that the fibers must undergo several changes in direction as it is fed from the packages to other associated machinery. Each time the fiber changes direction, particularly sharply, the chances of a fiber break are greatly increased because of the increased tension resulting from the changes in direction. Fiber breaks with such creels also cause interruptions in the manufacturing process and lead to the problem of unproductive downtime discussed above.
An additional problem with creels using multiple packages is related to the size of the yarn packages which can be provided and supported on a creel. That is, the amount of yarn is limited due to practicalities such as weight and space occupied by the package. For example, typical yarn packages of up to 12″ in diameter are utilized to provide a large amount of yarn to a high speed manufacturing process such as a diaper machine. However, a large number of packages of this size package can take up a lot of valuable manufacturing floor space when used with creel configurations of the background art.
To handle the problem due to the size of the multiple packages needed, background art creels for the OETO method are typically configured with the active package and standby package positioned at acute angles (i.e., less than 90°) relative to one another. However, as noted above, a problem with OETO creels with this type of configuration is the valuable floor space they take up in the manufacturing environment. In addition, unacceptable variations in threadline tension are common with these background art creels when using the OETO method.
U.S. Pat. No. 5,566,574 discloses a method for feeding fiber to a textile machine by utilizing a braking member and actuator to adjust the tension and feed rate of the thread or fiber in an attempt to address the tension problems discussed above. However, the '574 patent does not disclose the concept of utilizing a variable speed electrical motor for a driven roll, where the speed of the motor is determined based on a range of desired thread tensions and could improve the performance of the manufacturing process.
Further, manufacturing processes using an elastomeric thread or fiber like Spandex, which has a unique inherent finish texture that differs from threads or fibers used in the textile industry, requires an electrical motor feeding device that allows the Spandex to remain in contact with the driven feed roll attached to the motor. Furthermore, Spandex has a higher tensile strength specification and other characteristics that differ from fibers used in the textile industry. For example, threads or fibers typically used in the textile industry are specified in the range of 50-100 decitex (decigrams per kilometer) and tend to operate at lower rotation speeds of 1-50 feet/minute when being unwound from a package as compared to those used for elastomeric threads which typically are specified in the range of 600-1500 decitex and with higher rotation speeds of 300-400 feet/minute. Moreover, the '574 patent is not directed to operate with or feed systems that require high tack, elastomeric threads such as Spandex.
The aforementioned problems make the continuous processing of high tack, elastomeric fibers particularly problematic. Fiber tack and its associated problems have been addressed by using topical fiber additives (e.g., prior to winding) or by unwinding the package and re-winding it on a new mandrel. However, both approaches add additional expense to the manufacturing process. Furthermore some applications (e.g., manufacturing of diapers and other personal care products) require the use of as-spun thread or fiber that is substantially finish-free and, consequently, exhibits high tack.
Therefore, there is a need in the art for creels that: (1) allow packages to be changed without interrupting the manufacturing process; (2) hold a large number of packages for feeding fiber to high speed manufacturing processes in a relatively compact footprint; (3) minimize the changes in direction of the fiber during delivery to eliminate breaks and minimize tension; (4) provide a fast, reliable and continuous method of unwinding, feeding and delivering high tack elastomeric fibers from a package to a high speed manufacturing process.